Piezoelectric impact fuze



Aug. 29, 1967 JA-FFE ET AL I Q 3,339,090

PIEZOELECTRIC IMPACT FUZE Original Filed Oct. 15, 1963 INVENTORS, Hans Jaffe JnhrLA.Cc|rnB1g BY VanceEEmsweH Dean Gfihumaker igfloma a; Q Z

United States Patent 1 Claim. (Cl. 310-81) This application is a division of our earlier application Ser. No. 326,648, filed on Oct. 15, 1963 now abandoned.

This invention relates to a piezoelectric impact fuze and more particularly to a fuze of the piezoelectric type in which the entire assembly is encased in a potting compound to maintain the operating elements in their assembled position, the entire unit then being encased again in a monolithic plastic housing by pressure molding.

It is a primary object of this invention to provide a fuze, or the like, that is compact and possessing high operating temperature characteristics.

Another object is to provide a fuze in which springs and friction contacts are eliminated.

Another object is to provide a housing for the fuze elements that is unbreakable, completely waterproof and having negligible mechanical distortion at maximum operating temperatures.

A still further object of the invention is to provide adequate thermal insulation for the piezoelectric and semiconductor diode element of the fuze.

A final object is to provide a fuze that possesses a very small time delay, rapid rise time, adequate hold time, excellent repeatability of electrical output and which is easily manufactured by mass production.

With these and other objects in view which will become apparent as the specification develops, reference is made to the drawing wherein:

FIG. 1 is a longitudinal section taken through a fuze constructed in accordance with the invention;

FIG. 2 is an exploded perspective view of the operating elements of the fuze, the electric connections being shown in broken lines;

FIG. 3 is a perspective view of the connector support; and,

FIG. 4 is a perspective view of the fuze in completed form on a reduced scale.

Referring to the drawing, 1 indicates generally the fuze of the invention in its entirety.

The fuze 1 includes operating elements consisting of a connector 2 which is externally threaded along its rearward portion as at 3.

A connector support generally indicated at 4 is provided and consists of a ring portion 5 adapted to encircle connector 2 about its threaded portion and has an integral downwardly depending arm 6 which is bent inwardly as at 7 (see FIG. 3). Support 4 is held in position on connector 2 by nuts 8 and lock washer 9. (See FIG. 1.) When in assembled position, the nuts :and washer will hold support 4 for an electrical connection to connector 2.

An isolation diode 10 of semiconductor type is provided.

Piezoelectric elements for operating the fuze consist of a piezo ceramic annulus 11 having contact terminals 12 and 13, as seen in FIGS. 1 and 2.

An annular Weight 14 is provided for compressing ele- 3,339,990 Patented Aug. 29, 1967 m'ent 11 and has a reduced portion 15 which slidably fits into annulus 11.

Weight 14 is centrally bored as at 16 to provide a mounting hole for receiving a screw or the like (not shown) for mounting the device in a projectile, etc. A sleeve 17 is provided for insulation of the elements 11 and 14 when using a metal mounting screw or like fastening element.

18 denotes a potting compound and 19 a hardening plastic casing.

The electrical connections of the fuse comprises a lead 20 from connector 2 to diode 10, lead 21 from diode 20 to terminal 12 on element 11, and lead 22 from terminal 13 on element 11 to arm 7 of support 4.

In assembly, support 4 is fixed on connector 2 by nuts 8, diode 10 is electrically connected to 2 and to element 11 and element 11 is connected to arm 7 by lead 22. All connections are then soldered.

A layer of silicone grease is applied between loading weight 14 and element 11 to fill any possible air voids that could result in an increase in time delay of the fuze.

Connector 2 may be held in position temporarily for assembly by a snap ring or like element, not shown, which may encircle element 11 and pass through a hooked portion 23 of support 4, and then removed before the potting compound 18 is molded about the subassembly to maintain its position for a final molding thereof with a hardening plastic to form a housing 19, This molding is done under pressure in a mold (not shown) and under a heating of 250 F. The pressure of the molding operation is p.s.i.

After curing for approximately five minutes, the molded fuze is coated, by spraying, with a silver paint for electrical shielding.

The device of the invention is impact sensitive; the piezoelectric element 11 being compressed by the weight 14 as a result of impact to generate an electric impulse for firing a shell or the like, not shown.

The device may also be used as an accelerometer if desired since the induced voltages are functions of velocity and may also be used in parallel for multiple various tests.

Variations and modifications may be effected without departing from the scope of the novel concept of the present invention.

What is claimed is:

An impact electric impulse generator for a fuse, comprising in combination a piezoelectric ceramic annulus, an annular loading weight having a reduced portion slidably fitted into said annulus, there being .a central mounting bore in said loading weight, an insulating sleeve carried by said bore, a diode, a connector, a support fixed to said connector, electrical circuitry connecting said operating elements comprising a first lead connecting said connector to said diode, a second lead connecting said diode to said annulus, and a third lead connecting said annulus to said support and a plastic housing molded about said operating elements.

References Cited UNITED STATES PATENTS 2,871,787 2/1959 Rizer 102-702. 3,094,314 6/1963 Kearney 3108.7

MILTON O. HIRSHFIELD, Primary Examiner. J. D. MILLER, Assistant Examiner. 

